JP3104143B2 - Ultrasonic stirrer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic stirrer for stirring a liquid by using an elastic vibration generated by an ultrasonic actuator composed of a columnar piezoelectric vibrator as a driving source.

[0002]

2. Description of the Related Art As a closed stirring device, a magnetic stirrer is effective. A magnetic stirrer drives a rotor in a container with a magnet rotated by a motor to stir the liquid in the container. As the rotor, an iron piece or a magnet piece wrapped with Teflon or the like is used. Magnetic stirrers are also useful for open system agitation using containers such as beakers. By the way, the simplest stirring operation with a small amount is shaking by hand. However, there are cases where sufficient stirring cannot be achieved simply by shaking a small container. That is, satisfactory results may not be obtained simply by reducing the size of the experimental device in the macro amount. This is due to the lack of a high-performance magnetic stirrer that is small and capable of low speed and high torque. In order to stir a very small amount, it is necessary not only to reduce the size of the magnetic stirrer but also to improve the performance thereof in accordance with the downsizing of the container.

[0003] A shaking apparatus used for shaking a culture solution or the like in a container for a long time has been conventionally used.
In addition to being generally large and unsuitable for small amounts of shaking, there was also noise due to shaking, making it very difficult to shake at very low speeds. When it is necessary to maintain a constant temperature, methods such as immersing the container in constant temperature water or exposing the container to constant temperature circulating air are used, but it is difficult to seal them in a constant temperature room. However, temperature errors tend to occur, and it is difficult to keep the humidity constant.

[0004]

The conventional magnetic stirrer is difficult to miniaturize, and the performance decreases as the miniaturization is attempted. Therefore, it is difficult to stir at low speed and high torque. Was never used. A minute amount of stirring has not provided any useful measures, especially in closed systems.

[0005] Conventional shaking devices are generally large and are not suitable for shaking in very small amounts, but also have noise due to shaking, making it difficult to shake at very low speed. Further, since it is difficult to seal the device in a constant temperature room, it has been difficult to keep both the temperature and the humidity constant.

Therefore, in the present invention, by using an ultrasonic actuator as a drive source, it is possible to perform stirring at an extremely low speed and a high torque, and to make the apparatus smaller, lighter, lower in noise and lower in power consumption, and to reduce the temperature. Provided is an ultrasonic stirrer for stirring a small amount of liquid for the purpose of enabling shaking in a closed chamber where humidity is kept constant.

[0007]

According to a first aspect of the present invention, there is provided an ultrasonic stirrer which converts electric vibration into elastic vibration of ultrasonic waves by a piezoelectric vibrator, and stirs the liquid in the container by a force based on the elastic vibration. The piezoelectric vibrator comprises a columnar piezoelectric ceramic, and first and second electrodes respectively formed on both end faces perpendicular to the polarization axis of the piezoelectric ceramic, and At least one of the electrodes is divided into two parts that are insulated from each other, and has means for pressing an object against the side surface of the piezoelectric ceramic, and transmits the force received from the side surface to the liquid by applying the object to the liquid. Is characterized by stirring.

According to a second aspect of the present invention, in the ultrasonic stirrer, the object is a rotary rocking body that rotates or swings around a predetermined axis or a moving body that moves along a predetermined guide rail. It is characterized by.

According to a third aspect of the present invention, the object is the container.

According to a fourth aspect of the present invention, in the ultrasonic stirrer, at least a portion of the object is a magnetic material, and a stirrer at least a portion of a magnetic material immersed in the liquid is contained in the container. It is characterized by.

According to a fifth aspect of the present invention, in the ultrasonic stirrer, a drive circuit for supplying an excitation voltage to the piezoelectric vibrator outputs an AC pulse voltage as the excitation voltage, and a voltage value and an AC frequency of the AC pulse voltage. And a means for adjusting at least one of the pulse width and the pulse repetition frequency of the AC pulse voltage.

According to a sixth aspect of the present invention, in the ultrasonic stirrer, the piezoelectric vibrator generates AC power from an oscillation circuit that resonates and oscillates in a resonance circuit having a capacitance and an inductance of the piezoelectric vibrator as a main reactance component. It is characterized by receiving and being excited.

[0013]

In the driving section of the ultrasonic stirrer according to the first aspect, the frequency equal to the resonance frequency of the piezoelectric vibrator having the first and second electrodes on both end faces perpendicular to the polarization axis of the columnar piezoelectric ceramic is provided. Is applied to the piezoelectric vibrator through the first and second electrodes, the piezoelectric vibrator is excited and a one-way vibration displacement is generated on the side surface of the piezoelectric ceramic. When the object is in contact with the side surface of the piezoelectric ceramic, the vibration displacement is transmitted to the object, further transmitted from the object to the liquid, and the liquid is agitated. Thus, in the ultrasonic stirring device of the present invention, the liquid in the container can be stirred by using the one-way vibration displacement generated on the side surface of the piezoelectric ceramic as a driving source. Since the present apparatus has a high response speed to an electric input, pulse driving can be performed accurately and easily. In addition, since a holding force at the time of no input is large, accurate and uniform stirring of a small volume can be performed. Therefore, it is particularly useful for titration of a very small amount, shaking of a culture solution for a long time, and the like, as well as for a minute amount of a chemical reaction in a closed system. In addition, it can be driven with low power consumption, there is no noise, self-excited drive is possible, and it is easy to drive with batteries, so it can be used for a long time in a closed room where constant temperature and humidity are maintained. It is possible. In addition, super low speed
Since driving with high torque is possible, no gear is required, so that the device can be reduced in size and weight. Therefore, it is possible to stir a very small amount of liquid in a closed system or an open system.

Since at least one of the first and second electrodes is divided into two portions insulated from each other, the electrode provided on one of the portions is used as an electrode for a self-excited power supply. Can be used. Therefore, the ultrasonic stirring device of the present invention can be driven with low power consumption in a manner that can respond to changes in the environment.

In the ultrasonic stirrer according to the second aspect of the present invention, the object rotates around a predetermined axis, rotates around a predetermined axis, or moves along a predetermined guide rail. Mobile. When the rotary oscillator is in contact with the side surface of the piezoelectric ceramic, the vibration displacement is transmitted to the rotary oscillator, and the rotary oscillator rotates. When the moving body is in contact with the side surface of the piezoelectric vibrator,
The vibration displacement is transmitted to the moving body, and the moving body makes a linear motion along the direction of the polarization axis of the piezoelectric ceramic. The movement of the rotating rocker or the moving body is transmitted to the liquid in the container, and the liquid is stirred.

[0016] By providing two piezoelectric vibrators and inverting the rotation direction of the rotary oscillator by each of the piezoelectric oscillators, the rotation of the rotary oscillator can be determined by which of the piezoelectric oscillators is driven. The direction can be reversed. That is, the reversing motion within an arbitrary angle becomes possible.
In addition, by changing the amplitude or frequency of the AC signal applied to the piezoelectric vibrator within a certain range, the magnitude of the vibration displacement generated on the side surface of the piezoelectric ceramic can be arbitrarily controlled. The control of the rotation speed of the oscillating body becomes easier and more accurate. Therefore, not only can the rotation direction of the rotary oscillating body be reversed, but also its rotation speed can be accurately controlled from a very low speed to a high speed. Not only can stirring be possible, but also the reversing motion of the rotary oscillating body becomes possible, so that a very small amount of liquid can be shaken for a long time. Further, by providing a plurality of the piezoelectric vibrators, and by making the rotation direction of the rotary oscillator the same by them, it becomes possible to drive with higher torque,
More effective stirring becomes possible.

[0017] By providing two piezoelectric vibrators and further reversing the moving direction of the moving body by each piezoelectric vibrator, the moving direction of the moving body is determined by which of the piezoelectric vibrators is driven. Can be reversed. That is, the repetitive motion of the moving body becomes possible. In addition, by changing the amplitude or frequency of the AC signal applied to the piezoelectric vibrator within a certain range, the magnitude of the vibration displacement generated on the side surface of the piezoelectric ceramic can be arbitrarily controlled. Controlling the speed of movement of the body becomes easier and more accurate. Therefore, not only the repetitive motion of the moving body can be enabled, but also the speed of the motion can be accurately controlled from a very low speed to a high speed. Not only stirring becomes possible, but also shaking of a very small amount of liquid over a long period of time becomes possible. Further, a plurality of the piezoelectric vibrators are provided, each of the piezoelectric vibrators is sequentially driven, and the moving body is returned to the initial position by the lastly driven piezoelectric vibrator. When the first piezoelectric vibrator has been driven once, the first piezoelectric vibrator is driven again, and by repeating this, the moving body can be caused to repeat a motion obtained by combining an arbitrary linear motion. For example, by providing the four piezoelectric vibrators, not only can the moving trajectory of the moving body be square, but also a figure in which the end point and the start point of the Z-shape are connected by a straight line. . Therefore, more effective stirring is possible, and it is particularly useful for shaking a very small amount of liquid for a long time.

In the ultrasonic stirrer according to the third aspect, since the object is the container, the vibration displacement generated on the side surface of the piezoelectric ceramic is directly applied to the container without the rotation oscillating body or the moving body. Is transmitted to Therefore, more effective stirring becomes possible.

In the ultrasonic stirrer according to the fourth aspect, at least a part of the object is magnetized. on the other hand,
A stirrer that is at least partially magnetic is contained in the container, and the stirrer is immersed in the liquid. When the object moves due to the vibration displacement received from the piezoelectric ceramic, the stirrer also moves, so that the liquid in the container is stirred by the movement of the stirrer. Therefore, according to the ultrasonic stirring device of the present invention, more effective stirring of a very small amount of liquid becomes possible.

The ultrasonic stirrer according to claim 5, wherein an AC pulse voltage is output as the excitation voltage, and at least one of a voltage value of the AC pulse voltage and an AC frequency is adjusted; Means for adjusting at least one of the pulse width and the pulse repetition frequency of the voltage are provided in the drive circuit. Therefore, the movement speed of the object can be accurately controlled from a very low speed to a high speed, and further, the movement direction of the object can be reversed. Therefore, since the reversing motion of the rotary rocking body and the repetitive motion of the moving body are facilitated, a very small amount of liquid can be effectively stirred. In addition, since the moving speed of the object can be easily and continuously changed, the stirring effect is further increased. Further, since driving can be performed with low power consumption, there is no noise, ultra-low speed and high torque driving is possible, and no gear is required, so that the device can be reduced in size and weight.

In the ultrasonic stirrer according to the present invention, the piezoelectric vibrator supplies AC power from an oscillation circuit which resonates and oscillates in a resonance circuit having a capacitance and an inductance of the piezoelectric vibrator as a main reactance component. Received and excited.
Therefore, the ultrasonic stirring device of the present invention can provide a drive circuit that can cope with environmental changes such as external temperature. That is, since the movement speed of the object does not change due to a change in the external temperature or the like, uniform stirring can always be performed,
It can be used continuously in a wide temperature range from a few hundred degrees below freezing to around a few hundred degrees through normal temperature.

[0022]

FIG. 1 is a sectional view showing a first embodiment of an ultrasonic stirring device according to the present invention. In this embodiment, a piezoelectric vibrator 1 to which terminals P, Q, and R made of copper foil are attached, a rotating body 2, a friction material 3, a support 4, and an Sm-Co magnet 5
And a stirrer 6. The rotating body 2 is supported by a support 4, and the support 4 is fixed to the main body. Stirrer 6
Is charged into a glass Erlenmeyer flask containing a liquid. The Erlenmeyer flask is placed on the plate at the top of the body. The main body is made of plastic having chemical resistance and water resistance, and the upper part of the main body can be removed from the lower part of the main body.
The stirrer 6 is a Sm-Co magnet wrapped in Teflon. A switch is provided on a power supply circuit connecting the two piezoelectric vibrators 1, and an AC voltage is supplied to one of the piezoelectric vibrators 1 by switching the switch. In FIG. 1, a power supply circuit connecting the two piezoelectric vibrators 1 and a switch provided therebetween, a power supply circuit for supplying an AC voltage to the piezoelectric vibrator 1 and terminals P, Q, and R are omitted.

FIG. 2 is a perspective view of the piezoelectric vibrator 1. The piezoelectric vibrator 1 includes a columnar piezoelectric ceramic 20 and electrodes 21 provided on both end faces perpendicular to the polarization axis of the piezoelectric ceramic 20.
22 and 23. Piezoelectric ceramic 20 is 10m in diameter
m, height 10mm, material is TDK 91A material (product name)
And its resonance frequency is about 138 kHz. TDK
The 91A material has a large electromechanical coupling coefficient, and is therefore used in the embodiment here. The electrodes 21 and 22 are provided on the same surface and are insulated from each other. The electrode 21 is used as an electrode for applying an AC voltage to the piezoelectric vibrator 1, and the electrode 22 is used as an electrode for a self-excited power supply. The electrode 23 covers the entire other end surface.
Terminal P on electrode 21, terminal Q on electrode 22, electrode 2
A terminal R is provided on 3. The arrows in the figure indicate the vibration displacement that occurs on the side surface of the piezoelectric ceramic 20 in a resonance state when an AC signal is applied to the piezoelectric vibrator 1. By dividing the electrode provided on one end face into two parts and making them insulated from each other, not only self-excited driving becomes possible, but also one-sided vibration displacement occurs on the side surface of the piezoelectric ceramic 20. .

FIG. 3 is a plan view when the rotating body 2 is viewed from above. A plate-like Sm-Co magnet 5 is provided above the rotating body 2.
Is fixed. The Sm-Co magnet 5 is fixed on the plate surface of the rotating body 2 such that its center is overlapped with the center of the rotating body 2.

FIG. 4 is a plan view of the driving section of the embodiment shown in FIG. 1 when viewed from the side of the piezoelectric vibrator 1 along the axis of the rotating body 2. The rotating body 2 has a diameter of 39 mm and a thickness of 2.
A 5 mm disk, and a 5 mm diameter fixed to the center of the disk,
A friction material 3 is fixed to the plate surface of the disk in a ring shape having a width of 8 mm and a thickness of 1 mm concentric with the center of the disk. The friction material 3 is made of epoxy resin mixed with polyamide.

FIG. 5 is a graph showing the relationship between the first embodiment shown in FIG.
Second ultrasonic stirrer excluding Co magnet 5 and stirrer 6
It is sectional drawing which shows Example of (a). At the time of use, the upper part of the main body is removed, and the Erlenmeyer flask is directly fixed to the rotating body 7.

FIG. 6 is a sectional view showing a third embodiment of the ultrasonic stirrer according to the present invention. In this embodiment, the piezoelectric vibrator 1 used in the first embodiment shown in FIG.
A friction material 13, a support 14, a Sm-Co magnet 15,
And a stirrer 16. The linear motion body 12 is supported by a support 14, and the support 14 is fixed to the main body.
The stirrer 16 is placed in a glass microtube containing a liquid. The microtube is fixed to a plate surface on the upper part of the main body. The main body is made of plastic having chemical resistance and water resistance, and the upper part of the main body can be removed from the lower part of the main body. The stirrer 16 is formed by wrapping a Sm-Co magnet with Teflon. A switch is provided on a power supply circuit connecting the two piezoelectric vibrators 1, and an AC voltage is supplied to one of the piezoelectric vibrators 1 by switching the switch. In FIG. 6, a power supply circuit connecting the two piezoelectric vibrators 1 and a switch provided therebetween, a power supply circuit for supplying an AC voltage to the piezoelectric vibrator 1 and terminals P, Q,
R is omitted.

FIG. 7 is a plan view when the linear moving body 12 is viewed from above. A plurality of plate-like Sm-Co magnets 15 are fixed to the upper part of the linear motion body 12 at substantially equal intervals.

FIG. 8 is a plan view of the driving section of the embodiment shown in FIG. 6 when viewed from the side of the piezoelectric vibrator 1 along the thickness direction of the linear moving body 12. The linear motion body 12 has a rectangular plate having a side length of 39 mm and a thickness of 4 mm, and a length of 39 mm fixed around a straight line passing through the center of the plate surface of the rectangular plate and parallel to the direction of the polarization axis of the piezoelectric ceramic 20. And a prism having a width of 5 mm and a height of 16 mm. The prism is fixed to the rectangular plate by a fixing portion having a length of 39 mm and a width of 5 mm. Two rectangular grooves having a length of 37 mm, a width of 5 mm, and a height of 2 mm are provided on the plate surface of the rectangular plate, and the two grooves are arranged at equal intervals with the prism interposed therebetween. A friction material 13 is fixed to the bottom surface of the groove at a thickness of 1 mm. The friction material 13 is made of epoxy resin mixed with polyamide.

FIG. 9 is a graph showing the Sm− from the third embodiment shown in FIG.
FIG. 9 is a cross-sectional view illustrating a fourth embodiment of the ultrasonic stirring device from which the Co magnet 15 and the stirrer 16 have been removed. At the time of use, remove the upper part of the main body, and the micro tube is directly
To be fixed.

FIG. 10 is a configuration diagram of a power supply circuit for pulse driving when an rf pulse is applied. The waveform in the ellipse between the pulse generator and the mixer is the waveform generated by the pulse generator. The waveform in the ellipse between the signal generator and the mixer is the waveform generated by the signal generator. The waveform in the ellipse between the mixer and the power amplifier is a composite of the waveform generated by the pulse generator and the waveform generated by the signal generator. At the time of pulse driving, an AC signal indicating a waveform synthesized in this manner is applied to the piezoelectric vibrator 1. That is, by using such a power supply circuit, the voltage value and the AC frequency of the AC pulse voltage applied to the piezoelectric vibrator 1 can be adjusted, and the pulse width and the pulse repetition frequency of the AC pulse voltage can be adjusted. Becomes

In the first embodiment shown in FIG. 1, each of the electrodes 21, 22, 23 of the two piezoelectric vibrators 1 is a straight line passing through the center of the disk of the rotating body 2 and parallel to the polarization axis of the piezoelectric ceramic 20. And the side surface on which the electrode 22 is provided is in contact with the friction material 3. When driving the ultrasonic stirring device of the embodiment of FIG. 1, one of the piezoelectric vibrators 1 is driven by switching the switch. In this way, an AC signal having a frequency equal to the resonance frequency of the piezoelectric vibrator 1 is applied to the piezoelectric vibrator 1 via the terminal P provided on the electrode 21 and the terminal R provided on the electrode 23. Is done. The piezoelectric vibrator 1 is excited, and a one-way vibration displacement is generated on the side surface of the piezoelectric ceramic 20 along the direction of the polarization axis of the piezoelectric ceramic 20. The piezoelectric vibrator 1 is provided at a position where a straight line dividing the electrodes 21 and 22 is parallel to the disk surface of the rotating body 2, and the piezoelectric vibrator 1 is in contact with the friction material 3. At this time, since the piezoelectric vibrator 1 has a cylindrical shape, the shape of the portion where the piezoelectric vibrator 1 contacts the friction material 3 is a straight line connecting both end faces of the piezoelectric vibrator 1 and being perpendicular to the both end faces.
The straight line is perpendicular to a straight line (length 12 mm) connecting the center of the straight line and the center of the plate surface of the disk. The one-way vibration displacement generated on the side surface of the piezoelectric ceramic 20 is transmitted from the linear portion to the rotating body 2 via the friction material 3, and the rotating body 2 rotates around its axis. At this time, the friction material 3 not only prevents wear of the piezoelectric ceramic 20 and the disk of the rotating body 2 due to rotation, but also reduces electromagnetic noise caused by high voltage generated between the rotating body 2 and the piezoelectric vibrator 1 due to rotation. To prevent. Sm-C fixed to the disk of the rotating body 2 with the rotation of the rotating body 2
The o magnet 5 also rotates around the axis of the rotating body 2. At this time,
The stirrer 6 also rotates around the center thereof in synchronization with the rotation of the Sm-Co magnet 5. The rotation of the stirrer 6 stirs the liquid in the Erlenmeyer flask.

By changing the frequency of the AC signal applied to the piezoelectric vibrator 1 within a certain range, not only the magnitude of the vibration displacement generated on the side surface of the piezoelectric ceramic 20 but also its direction can be arbitrarily controlled. . Therefore, the control of the rotation speed of the rotating body 2 and the reverse rotation driving become possible, so that the stirrer 6
, And the rotation of the stirrer 6 can be repeatedly reversed at an arbitrary angle, and an effective stirring action can be provided to the liquid in the Erlenmeyer flask.

The rotating body 2 can be rotated in the reverse direction only by switching the switches without changing the amplitude or frequency of the AC signal applied to the piezoelectric vibrator 1. This is because the directions in which the two piezoelectric vibrators 1 rotate the rotating body 2 are opposite. Rather than changing the amplitude or frequency of the AC signal applied to the piezoelectric vibrator 1, the direction of rotation of the rotating body 2 is changed by switching the switch, and the amplitude or frequency of the AC signal is kept constant. , The magnitude of the vibration displacement generated on the side surface of the piezoelectric ceramic 20 can be arbitrarily controlled, so that the reverse rotation drive and the control of the rotation speed of the rotating body 2 become easier and more accurate. . Therefore, the stirrer 6 can be repeatedly inverted at an arbitrary angle and its movement speed can be controlled, so that the effect of stirring the liquid can be increased.

FIG. 11 is a characteristic diagram showing the relationship between the admittance amplitude and phase with respect to the frequency of the piezoelectric vibrator 1. It resonates around 140 kHz and anti-resonates at about 168 kHz. An admittance peak at a resonance frequency of about 140 kHz is split into two resonance cracks. This is because the electrode provided on one end face of the piezoelectric ceramic 20 is divided into two to form the electrodes 21 and 22, which are insulated from each other.

FIG. 12 is a characteristic diagram showing the relationship between the applied voltage and the rotation speed of the rotating body 2 in the first embodiment of FIG.
The rotation speed has a linear relationship with the applied voltage, and its inclination is about 0.4 rpm / V. Note that the frequency of the applied voltage signal is substantially equal to the resonance frequency of the piezoelectric vibrator 1, and
38 kHz.

FIG. 13 shows the relationship between the pulse width and the rotation angle per pulse when the pulse driving is performed at an applied voltage of 100 Vp-p and a frequency of about 138 kHz in the first embodiment of FIG. It is a characteristic diagram. Assuming that the time required for N rotations is T and the pulse repetition frequency is fp, the rotation angle θ per pulse is given by equation (1). θ (deg.) = 360N / (fp · T) (1) When the pulse width is 20 ms or more, the pulse width and the rotation angle per pulse have a substantially linear relationship. It can be seen that the time from the start to the constant and the time from the release of the voltage to the stop of the driving are at least several tens of milliseconds or less. Compared with the fact that the natural stoppage of the electromagnetic motor is several hundred milliseconds to several seconds, the response speed of the drive source of this device is extremely high. The minimum pulse width that can be operated is 1 ms, and the rotation angle at that time is about 0.0
03 °.

The pulse drive is employed as a method of activating the ultrasonic stirring device of the first embodiment shown in FIG. 1. The pulse drive is more suitable for accurate control of the rotation speed of the rotating body 2 than the continuous drive. Because it is. If a rotary encoder is used together with the pulse drive, more accurate control of the rotation speed can be performed. The rotary encoder is used to convert an angle into an electric signal. The ultrasonic stirrer of the present embodiment used an incremental type that sequentially generates a pulse for each unit angle. The highest resolution of the incremental type is 6000 pulses per rotation, so 1
The rotation angle per pulse is 0.06 °. Further, as for the error, since the minimum rotation angle in pulse driving is 0.003 ° in FIG. 13 and the resolution of the incremental type is 0.06 °, the maximum error is 5%, which is an extremely small value. Therefore, when the incremental type is used together, the control of the rotation speed of the rotating body 2 is further improved.
In this way, the stirring effect of the minute amount of liquid by the stirrer 6 is increased, which is effective not only for chemical reaction but also for titration.

In the second embodiment shown in FIG. 5, the Erlenmeyer flask is directly fixed to the rotating body 2. Therefore, at the time of driving of the present embodiment, the liquid in the Erlenmeyer flask is stirred with the rotation of the rotating body 2. Further, since the rotating body 2 can be reversed at an arbitrary angle or its movement speed can be adjusted, the effect of stirring the liquid is further enhanced.

In the third embodiment shown in FIG. 6, the electrodes 21, 22, and 23 of the two piezoelectric vibrators 1 pass through the center of the rectangular plate surface and are parallel to the direction of the polarization axis of the piezoelectric ceramic 20. The side on which the electrode 22 is provided is in contact with the friction material 13 at a position symmetrical to the straight line. When the ultrasonic stirrer of the present embodiment is driven, one of the piezoelectric vibrators 1 is driven by switching the switch. In this way, an AC signal having a frequency equal to the resonance frequency of the piezoelectric vibrator 1 is applied to the piezoelectric vibrator 1 via the terminal P provided on the electrode 21 and the terminal R provided on the electrode 23. Is done. The piezoelectric vibrator 1 is excited, and a one-way vibration displacement is generated on the side surface of the piezoelectric ceramic 20 along the direction of the polarization axis of the piezoelectric ceramic 20. The piezoelectric vibrator 1 is provided at a position where a straight line dividing the electrodes 21 and 22 is parallel to the surface of the rectangular plate of the linear moving body 12, and the piezoelectric vibrator 1 is in contact with the friction material 13. . At this time, since the piezoelectric vibrator 1 has a columnar shape, the shape of the portion where the piezoelectric vibrator 1 is in contact with the friction material 13 is a straight line connecting both end faces of the piezoelectric vibrator 1 and being perpendicular to the both end faces. The shortest distance between the straight line and the straight line passing through the center of the plate surface of the rectangular plate and parallel to the direction of the polarization axis of the piezoelectric ceramic 20 is 12 mm. The one-way vibration displacement generated on the side surface of the piezoelectric ceramic 20 is transmitted from the linear portion to the linear moving body 12 via the friction material 13, and the linear moving body 12 linearly moves in the direction of the polarization axis of the piezoelectric ceramic 20. . At this time, the friction material 13 is moved by the piezoelectric ceramic 20 and the linear moving body 1 by linear motion.
In addition to preventing wear of the piezoelectric vibrator 2, electromagnetic noise caused by a high voltage generated between the linear motion body 12 and the piezoelectric vibrator 1 due to linear motion is prevented. Sm-C fixed to the rectangular plate of the linear moving body 12 with the movement of the linear moving body 12
The o magnet 15 also moves linearly. At this time, the stirrer 16 also moves in conjunction with the movement of the Sm-Co magnet 15. The liquid in the microtube is stirred by the movement of the stirrer 16.

By changing the frequency of the AC signal applied to the piezoelectric vibrator 1 within a certain range, not only the magnitude of the vibration displacement generated on the side surface of the piezoelectric ceramic 20 but also the direction thereof can be arbitrarily controlled. Thus, it is possible to control the moving speed of the linear moving body 12 and to perform the driving in the reverse direction, that is, the repetitive motion, so that the repetitive motion of the stirrer 16 and the control of the moving speed can be performed, and the liquid in the microtube can be effectively stirred Can have an effect.

The linear motion body 12 can be driven in the reverse direction only by switching the switches without changing the amplitude or frequency of the AC signal applied to the piezoelectric vibrator 1. This is because the directions in which the two piezoelectric vibrators 1 move the linear motion body 12 are opposite. Instead of changing the amplitude or frequency of the AC signal applied to the piezoelectric vibrator 1, the direction of movement of the linear motion body 12 is changed by switching the switch, and the amplitude or frequency of the AC signal is further changed. By changing the magnitude within a certain range, the magnitude of the vibration displacement generated on the side surface of the piezoelectric ceramic 20 can be arbitrarily controlled, so that the repetitive motion and the motion speed of the linear motion body 12 can be controlled more easily and accurately. Become. Therefore, the stirring effect of the stirrer 16 can be increased.

In the fourth embodiment shown in FIG. 9, the microtube is directly fixed to the linear moving body 12. Therefore, at the time of driving in the present embodiment, the liquid in the microtube is stirred with the movement of the linear moving body 12. In addition, linear motion body 1
2 can be repeatedly moved or the movement speed can be adjusted, so that the effect of stirring the liquid is further enhanced.

[0044]

According to the ultrasonic stirring device of the present invention, an ultrasonic actuator is used as a driving source. Electrodes are provided on both end faces perpendicular to the polarization axis of the columnar piezoelectric ceramic. The electrode provided on one end face is divided into two and insulated from each other, and the electrode provided on the other end face covers the entire end face. A piezoelectric vibrator is made of such a piezoelectric ceramic and electrodes. By dividing the electrode formed on at least one end face of the piezoelectric vibrator into two parts insulated from each other as described above and using two electrodes, one electrode is used as an electrode for a self-excited power supply. be able to. Therefore, the ultrasonic stirrer of the present invention can be driven stably with respect to environmental changes such as temperature and with low power consumption. When an AC signal having a frequency equal to the resonance frequency is applied to the piezoelectric vibrator, the piezoelectric vibrator is excited and a one-sided vibration displacement is generated on the side surface of the piezoelectric ceramic along the direction of the polarization axis of the piezoelectric ceramic. This vibration displacement is transmitted to the object via the friction material, and the object moves. The friction material at this time not only prevents wear due to contact between the piezoelectric ceramic and the object, but also prevents electromagnetic noise caused by a high voltage generated between the piezoelectric vibrator and the object during driving. Since the response speed to the electric input is high, the pulse driving can be performed accurately and easily, and the holding power at the time of no input is large, so that the precise and uniform stirring of the minute volume can be performed. Therefore, not only a small amount of chemical reaction in a closed system,
It is particularly useful for titration of a very small amount or shaking of a culture solution for a long time. In addition, it can be driven with low power consumption, there is no noise, self-excited drive is possible, and it is easy to drive with batteries, so it can be used for a long time in a closed room where constant temperature and humidity are maintained. It is possible. Furthermore, since ultra-low speed and high torque driving is possible, no gear is required, so that the device can be reduced in size and weight. Therefore, it is possible to stir a very small amount of liquid in a closed system or an open system.

In addition to the case where the object is the container itself, there are also cases where the object is a rotary rocking body or a moving body. When the object is a container, the vibration displacement generated on the side surface of the piezoelectric ceramic is directly transmitted to the container to move the container and agitate the liquid in the container. When the object is a rotary rocking body or a moving body, the vibration displacement generated on the side surface of the piezoelectric ceramic moves the rotary rocking body or the moving body, and the movement stirs the liquid in the container.

By adopting a structure in which at least a part of the object is a magnetic substance and at least a part of the stirrer immersed in the liquid in the container is a magnetic substance,
Since the stirrer moves with the movement of the object, the liquid in the container is stirred.

By adopting a structure in which two piezoelectric vibrators are provided and the moving direction of the object by each piezoelectric vibrator is reversed, the moving direction of the object is controlled by which of the piezoelectric vibrators is driven. be able to. In addition, by changing the amplitude or frequency of the AC signal applied to the piezoelectric vibrator within a certain range, the magnitude of the vibration displacement generated on the side surface of the piezoelectric ceramic can be arbitrarily controlled. Speed control becomes easier and more accurate. Therefore, the reversing motion of the rotary rocking body at an arbitrary angle and the repetitive motion of the moving body can be performed, and the speed of the movement can be freely controlled, so that the effect of stirring a very small amount of liquid can be increased. If three or more piezoelectric vibrators are used and the respective piezoelectric vibrators are arranged so that the moving direction of the object is the same, further high torque driving can be realized.
Also, by using a plurality of piezoelectric vibrators, by setting the direction of movement of the object by each piezoelectric vibrator, the movement distance and the movement speed to predetermined values, by matching the start point and the end point of the movement trajectory of the object, The object can be maintained in motion having a predetermined period. In this way, more effective stirring can be performed, and it is particularly useful for shaking a very small amount of liquid over a long period of time.

In the ultrasonic stirring device of the present invention, pulse driving can be performed in addition to continuous driving. An AC pulse voltage is output as an excitation voltage, and a means for adjusting at least one of a voltage value and an AC frequency of the AC pulse voltage and a means for adjusting at least one of the pulse width and the pulse repetition frequency of the AC pulse voltage are driven. By employing the structure provided in the circuit, the magnitude and direction of the vibration displacement generated on the side surface of the piezoelectric ceramic can be freely changed. Therefore, since the moving direction and the moving speed of the object can be freely adjusted, the reversing movement of the rotary oscillating body and the repetitive movement of the moving body can be performed, and the moving speed can be freely adjusted. In this way, the effect of stirring a very small amount of liquid can be increased. Also,
The shaking effect of the micro solution over a long period of time can also be increased.

In the ultrasonic stirrer according to the present invention, the piezoelectric vibrator is excited by receiving AC power from an oscillation circuit which resonates and oscillates in a resonance circuit whose main reactance component is the capacitance and inductance of the piezoelectric vibrator. You. Therefore, the ultrasonic stirring device of the present invention can provide a drive circuit that can cope with environmental changes such as external temperature. In other words, the speed of movement of the object does not change due to changes in the external temperature, etc. It can be used.

By using a rotary encoder together with the pulse drive, the movement speed of the object can be controlled more accurately. Therefore, the effect of stirring a very small amount of liquid can be further increased, which is particularly useful for shaking a very small amount of solution for a long time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of an ultrasonic stirring device according to the present invention.

FIG. 2 is a perspective view of the piezoelectric vibrator 1. FIG.

FIG. 3 is a plan view when the rotating body 2 is viewed from above.

FIG. 4 is a plan view of the driving unit of the embodiment shown in FIG. 1 when viewed from the side of the piezoelectric vibrator 1 along the direction of the axis of the rotating body 2;

FIG. 5 is a sectional view showing a second embodiment of the ultrasonic stirrer in which the Sm-Co magnet and the stirrer 6 are removed from the first embodiment shown in FIG. 1;

FIG. 6 is a sectional view showing a third embodiment of the ultrasonic stirring device of the present invention.

FIG. 7 is a plan view when the linear moving body 12 is viewed from above.

FIG. 8 is a plan view of the driving unit of the embodiment shown in FIG. 6 when viewed from the side surface direction of the piezoelectric vibrator 1 along the thickness direction of the linear moving body 12.

FIG. 9 shows an Sm-Co magnet 1 according to the third embodiment shown in FIG. 6;
Sectional drawing which shows the 4th Example of the ultrasonic stirring device except 5 and the stirring element 16.

FIG. 10 is a configuration diagram of a power supply circuit for pulse driving when an rf pulse is applied.

FIG. 11 is a characteristic diagram showing the relationship between the amplitude and phase of admittance with respect to the frequency of the piezoelectric vibrator 1.

FIG. 12 is a characteristic diagram showing a relationship between an applied voltage and the number of rotations of a rotating body 2 in the ultrasonic stirring device of FIG.

FIG. 13 shows a case where the applied voltage is 1
FIG. 9 is a characteristic diagram showing a relationship between a pulse width and a rotation angle per pulse when a pulse drive at 00 Vp-p and a frequency of about 138 kHz is performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 2 Rotating body 3 Friction material 4 Support 5 Sm-Co magnet 6 Stirrer 12 Rotating body 13 Friction material 14 Support 15 Sm-Co magnet 16 Stirrer 20 Piezoelectric ceramic 21 Electrode 22 Electrode 23 Electrode

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B01F 11/00-11/04

Claims (6)

(57) [Claims] 1. A device for converting electric vibration into ultrasonic elastic vibration by a piezoelectric vibrator and agitating a liquid in a container by a force based on the elastic vibration, wherein the piezoelectric vibrator comprises a columnar piezoelectric ceramic; First and second electrodes respectively formed on both end faces perpendicular to the polarization axis of the piezoelectric ceramic, and at least one of the first and second electrodes is divided into two parts insulated from each other An ultrasonic stirrer, comprising: means for pressing an object against a side surface of the piezoelectric ceramic, and stirring the liquid by transmitting a force received by the object from the side surface to the liquid. 2. The apparatus according to claim 1, wherein the object is a rotary rocking body that rotates or swings around a predetermined axis or a moving body that moves along a predetermined guide rail. Ultrasonic stirrer. 3. The ultrasonic stirring device according to claim 1, wherein the object is the container. 4. The container according to claim 1, wherein at least a part of the object is made of a magnetic material, and a stirrer made of at least a part of the object that is immersed in the liquid is made of a magnetic material. Ultrasonic stirrer. 5. A driving circuit for supplying an excitation voltage to the piezoelectric vibrator outputs an AC pulse voltage as the excitation voltage,
Claims: It comprises means for adjusting at least one of a voltage value and an AC frequency of the AC pulse voltage, and means for adjusting at least one of a pulse width and a pulse repetition frequency of the AC pulse voltage. Item 6. The ultrasonic stirring device according to any one of Items 1 to 4. 6. The piezoelectric vibrator is characterized in that it is excited by receiving AC power from an oscillating circuit that resonates and oscillates in a resonance circuit whose main reactance component is the capacitance and inductance of the piezoelectric vibrator. The ultrasonic stirring device according to claim 1.